The occurrence of fibromyalgia-like syndromes in a general female population.

In an epidemiological survey of females aged 20-49 years in Arendal, Norway, 217 persons with musculoskeletal pain were examined for the presence of fibromyalgia as defined by the ACR criteria of 1990. Forty females with fibromyalgia were found whereas 129 females had chronic musculoskeletal pain of more than three months duration but failed to meet the criteria. Two females suffered from nonrheumatic disorders which could explain their musculoskeletal pain. Forty-six females had pain of less than three months duration. Somewhat surprising, the presence of tender points and symptoms regarded as typical of fibromyalgia were rather frequently observed among the females who failed to satisfy the ACR 1990 criteria. No other diseases were found which could explain their complaints or clinical findings. The presence of fibromyalgia-like syndromes is suggested, and the classification and nature of such syndromes are discussed.